Due to excellent separation capacity for complex mixtures of chemicals, comprehensive two-dimensional gas chromatography (GC × GC) is being utilized with increasing frequency for metabolomics ...analyses. This review describes recent advances in GC × GC method development for metabolomics, organismal sampling techniques compatible with GC × GC, metabolomic discoveries made using GC × GC, and recommendations and best practices for collecting and reporting GC × GC metabolomics data.
•The excellent separation capacity of GC × GC is well suited for metabolomics.•Methods are being developed to optimize metabolome sampling and analysis.•GC × GC metabolome analyses are moving toward identifying mechanisms.•Data reporting recommendations are provided to optimize data sharing via new metabolomics databases.•Best practices for GC × GC metabolomics analyses are described.
•A robust method for vacuum GC×GC-TOFMS was developed.•Run times were 2.7 times shorter using the vacuum method than a conventional method.•Vacuum GC×GC-TOFMS yielded a lower peak capacity than the ...conventional GC×GC-TOFMS.•Vacuum and convention GC×GC-TOFMS produced a similar number of peaks-per-minute.
The analysis of thermally labile and high-boiling point compounds by gas chromatography (GC) can be a challenge. One technique to overcome these challenges is low-pressure GC, which uses the vacuum produced from the mass spectrometer and wide-bore columns to elute compounds at significantly lower temperatures. While GC-MS is a powerful technique, comprehensive two-dimensional gas chromatography (GC × GC), allows for resolution of compounds that would typically coelute using GC. In this study, a pesticide standard mixture (8270 MegaMix Standard) was analyzed using a conventional GC × GC-TOFMS configuration (0.25 mm inner diameter (i.d.) to a 0.18 mm i.d. column) and low-pressure GC × GC-TOFMS configuration (0.53 mm i.d. to a 0.53 mm i.d. column). Elution temperatures, sensitivity, and peak capacity were investigated for both configurations. Compounds eluted an average of 30 °C less on the low-pressure GC × GC-TOFMS configuration compared to the conventional GC × GC-TOFMS configuration. Moreover, the compounds were separated in ∼13 min on the low-pressure GC × GC-TOFMS as opposed to 33 min for conventional GC × GC-TOFMS. However, due to the wide-bore columns and faster runtimes the low-pressure GC × GC-TOFMS had a lower, β corrected 2D peak capacity, nc,β,2D, of 1260 while the conventional GC × GC-TOFMS was 3588. Interestingly, both configurations yielded a similar peak capacity production of 93 peaks/min and 107 peaks/min for low-pressure and conventional GC × GC-TOFMS, respectively. A “real world” sample of diesel fuel was tested on the low-pressure and conventional GC × GC-TOFMS configurations and similar results were obtained compared to the pesticide standard mix except the peak capacity production of the low-pressure GC × GC-TOFMS configuration was higher than that of the conventional GC × GC-TOFMS method.
Conventional volatile organic compound (VOC) monitoring based on thermal desorption - gas chromatography–mass spectrometry (TD-GC–MS) or gas chromatography-flame ionization detector (TD-GC-FID) is ...relatively cumbersome and expensive. In this study commercial off the shelf low-cost and low-power photo-ionization detector (PID) sensors are used as simple detectors in VOC analysis systems based on GC, including a miniaturised GC × GC device with portable, low-cost, and low-energy-consumption features. PID sensors produce a voltage signal positively proportional to VOC concentration, which when incorporated into a TD-GC system gave limit of detection of 0.02 ppbV for isoprene. To test PID performance in real-world applications, PID sensors were deployed as (i) a second alternative detector in a GC-Quadruple Time Of Flight Mass spectrometry (GC-Q-TOF-MS), and (ii) the main detector in a compact two-dimensional gas chromatograph (GC × GC). PID sensors with 10.6 eV and 11.7 eV lamps were used to measure eight toxic chemicals including organic sulfide and organic phosphonates via GC; two species were ionized by a 10.6 eV lamp and four species by the 11.7 eV lamp. Commercially available low-cost PIDs designed for standalone could be straightforwardly and effectively re-used as detectors in compact GC × GC systems, in this work showing excellent VOC sensitivity, fast response and low operational demands compared to comparable field instruments based on GC-FID or MS.
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•PID as detector of a compact GC × GC shows similar performance with GC-FID.•PID sensor acts as a detector in a GC-Q-TOF-MS for VOC measurements.•PID lamps show different ionization effect on organic insecticides.
•A Tier α (<1 mL) Sustainable Aviation Fuel prescreening process is reported.•Eight critical properties are predicted with uncertainty quantification.•Predictions leverage GC × GC data and a 1226 ...hydrocarbon database of compounds.•Predictions are evaluated against experimental measurements of 20 SAFs.•Uncertainty quantification approximates the variance from novel molecules.
Fuels derived from sustainable feedstocks have significant potential to reduce greenhouse gas emissions associated with aviation. These alternative aviation fuels need to meet comprehensive safety and compatibility requirements established by an ASTM committee to achieve approval. To date, only seven annexes that define the property and compositional requirements for alternative fuels have been approved due, in part, to the significant cost and time required for evaluation and approval. Here, a Tier α sustainable aviation prescreening tool has been developed to predict the acceptability of novel SAF candidates, with the minimal volume required. Two-dimensional gas chromatography was used to determine the composition and size distribution of 20 alternative fuels, and Monte Carlo sampling was subsequently performed with a hydrocarbon database to predict eight properties that are important for combustor operability. These predicted properties were compared to experimentally measured properties, and uncertainty quantification was performed to validate the Tier α prescreening tool. The result of this validation suggests that four out of eight property confidence intervals are valid. Untuned predictions for properties with lower property variance across a given hydrocarbon type and carbon number, such as density and flash point, perform better than properties with significant property variance, such as freeze point and viscosity. The Tier α evaluation is outside of the ASTM evaluation process; however, this tool can provide feedback on downstream approval issues and facilitate fuel producer chemical process modeling thereby de-risking technology development. Thus, Tier α provides an early, rapid, and cost-effective evaluation for SAF candidates that requires minimal material volumes.
► A solvent-free ultrasound assisted extraction of lipids from fresh microalgae. ► Nannochloropsis oculata was chosen as a microalgae model. ► Influence of operating parameters on the extraction ...yields will be studied. ► Response surface methodology was used to study the performance of the extraction.
In order to comply with criteria of green chemistry concepts and sustainability, a new procedure has been performed for solvent-free ultrasound-assisted extraction (UAE) to extract lipids from fresh Nannochloropsis oculata biomass. Through response surface methodology (RSM) parameters affecting the oil recovery were optimized. Optimum conditions for oil extraction were estimated as follows: (i) 1000W ultrasonic power, (ii) 30min extraction time and (iii) biomass dry weight content at 5%. Yields were calculated by the total fatty acids methyl esters amounts analyzed by GC–FID–MS. The maximum oil recovery was around 0.21%. This value was compared with the one obtained with the conventional extraction method (Bligh and Dyer). Furthermore, effect of temperature on the yield was also investigated. The overall results show an innovative and effective extraction method adapted for microalgae oil recovery, without using solvent and with an enable scaling up.
•A new LJF is reported primarily composed of C6-C18 mono-, di-, and tri-cycloalkanes.•The LJF exhibited complementary material compatibility to existing SAF pathways.•Bulk properties of LJF 10% blend ...with a conventional fuel are reported.•LJF 10 vol% blend meets the ASTM D7566 Table 1 required properties.•Removal of any C17+ carbon molecules by distillation would achieve higher blend ratios.
Sustainable aviation fuels (SAFs) must demonstrate specific physical and chemical properties as well as material compatibility (i.e., seal swell) to be used as aviation turbine fuels. Several alternative jet fuels incorporated in ASTM D7566 are comprised mainly of n/iso-alkanes and can only be blended up to 50 vol% due to material compatibility and density issues. Prior work illustrated the ability of cycloalkanes to replace the swelling potential of aromatics required for material compatibility. Here, we report the first archival documentation of a feedstock and chemical process to yield a product composition that could complement 5 existing SAF ASTM D7566 annexes. A lignin-based jet fuel (LJF) blend component is generated and composed of mostly C6–C18 mono, di, and tri-cycloalkanes. The neat LJF was blended with conventional jet fuel at 10 vol% (LJF blend) to simulate a potential qualification goal. Fuel properties critical to engine operability (ATSM D4054 Tier 3 & 4) were either predicted or experimentally tested based on the volume availability. All LJF-blended operability properties fall within the experience range of conventional jet fuel, with neat o-ring swelling exceeding the typical range of conventional fuels. These results support the potential use of this LJF pathway to complement other SAF pathways and achieve 100% drop-in SAF.
Multidimensional gas chromatography Marriott, Philip J.; Chin, Sung-Tong; Maikhunthod, Bussayarat ...
TrAC, Trends in analytical chemistry (Regular ed.),
04/2012, Volume:
34
Journal Article
Peer reviewed
► Concepts of comprehensive two-dimensional gas chromatography (GC×GC) are reviewed. ► Multidimensional gas chromatography (MDGC) has witnessed a resurgence of interest. ► Designs of flow-switching ...devices and recent applications in MDGC are reviewed. ► A generic platform design offers GC×GC, MDGC, and integrated GC×GC/MDGC systems. ► MDGC and GC×GC represent a continuum of multi-column analytical methods.
Analytical multidimensional gas chromatography (MDGC) and the excellent separation efficiency it achieves serve advanced characterization of complex volatile and semi-volatile samples, which is unlikely to be accomplished by single-dimensional chromatography. Here, we provide a technical overview of recent method implementation in MDGC, for both the classical sense (i.e. conventional heart-cut MDGC), including recent approaches to MDGC, and the comprehensive two-dimensional gas chromatography (GC×GC) variant.
We summarize selected applications in diverse fields that best typify the role of these methods. We also draw attention to concepts (e.g., orthogonality of separation mechanisms and recently introduced microfluidic technology), and briefly comment on compatibility of detection systems.
As a guide to potential opportunities for continued innovation in multidimensional applications, we highlight the capabilities of GC platforms that either combine various GC×GC and MDGC arrangements or offer alternative operational modes for implementation of these methods.
Mechanical recycling of mixed packaging waste has limitations due to challenging separation into pure polyolefin streams which often leads to low quality recyclates. A solution to improve overall ...recycling rates of polyolefins is chemical recycling. One promising approach is conversion into a liquid product via pyrolysis and subsequent steam cracking of the pyrolysis oil towards light olefins. In this study, distilled fractions of pyrolysis oils from PE and PP-rich waste were characterized via GC × GC including normal and reversed-phase column configurations with a special focus on oxygenated components. Distilled pyrolysis oils were subsequently steam cracked in 20/80 weight‐based blends with conventional naphtha. All pyrolysis oil samples contained substantial amounts of oxygenates (1–10 wt%) which poses a huge challenge for steam cracker feedstocks and it was found that ketones are the most prevailing oxygenate group. Steam cracking experiments showed slightly increased ethylene yields of the blends compared to pure fossil naphtha, with the PE-derived samples outperforming the PP-derived samples. Furthermore, diesel-range distillation cuts led to higher formation of heavy products compared to the naphtha-range cuts. Increased formation of CO was observed as a consequence of the substantial oxygen contamination which can be a deal-breaker in industrial steam crackers. This work shows that distilled pyrolysis oils with conventional naphtha are promising steam cracking feedstocks if intermediate processing steps are performed to remove the oxygenates and other impurities using, for instance, hydrotreatment. With the findings of this work, such upgrading processes can be designed in a more effective way.
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•Comprehensive analysis of post-consumer plastic waste pyrolysis oils.•Combining normal and reversed-phase GC×GC-FID/qMS with focus on oxygenates.•Between 1.1 and 10.3 wt% of oxygenates with ketones being most prevailing species.•PP-derived pyrolysis oils contain mostly branched oxygenates.•High ethylene yields along with high amounts of heavy products and CO formation.
Mineral oil hydrocarbons (MOH) contain a wide structural diversity of molecules, for which the reference method of analysis is the online coupled liquid chromatography-gas chromatography with flame ...ionization detection (LC-GC-FID). These compounds are very heterogeneous from a toxicological viewpoint, and an accurate risk assessment when dealing with a MOH contamination can only be performed if sufficient information is available on the types of structures present (i.e., number of carbons, degree of alkylation, number of aromatic rings). Unfortunately, the separation performances of the current LC-GC-FID method are insufficient for such characterization, not even mentioning the possible coelution of interfering compounds which additionally hinder MOH determination. Comprehensive two-dimensional gas chromatography (GC × GC), while mostly used for confirmation purposes in the past, starts to prove its relevance for overcoming the weaknesses of the LC-GC method and reaching even better the analytical requirements defined in the latest EFSA opinion. The present paper therefore aims at highlighting how GC × GC has contributed to the understanding of the MOH topic, how it has developed to meet the requirements of MOH determination, and how it could play a role in the field for overcoming many of the current analytical and toxicological challenges related to the topic.
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